It is important to say what kind of car, what year and how many miles. Without that info it is hard to give advice. Some cars have a specialized market, like Mustangs or convertibles or diesel engines. Knowing that adds to what your Freepers can tell you. Also, investigate what your model is selling for by searching online.
In general, the car should be as clean as possible. Don’t do any repairs that do not show. If the brakes work, don’t touch them. I use Craigslist. Start with make, model, year and price. I won’t even glance at an ad that leaves that out. Next, mileage and condition. If it has 120k miles and the interior has a few minor rips and tears, provide that information with relevant pictures. Put all the positives first but do not skip over the negatives. If it has been smoked in, say so. You don’t want somebody driving two hours to see a car only to find out you left out relevant details, like there was a dead body in the trunk in a hot parking lot for two weeks and even your dog won’t go near it.
“...like there was a dead body in the trunk in a hot parking lot for two weeks and even your dog won’t go near it.”
In a related story: